A file system may be implemented by an operating system to define and manage a volume, such as determining how files are named, stored, organized, allocated, or otherwise managed on the volume. Allocation of space on a volume by components down-level of the file system may be unsafe. For instance, uncoordinated attempts by the file system and down-level components to allocate or operate upon the same space in the volume may result in data corruption, deadlocks, and/or loss of the volume.